Initial Stress Parameter Research Articles

Magneto-thermoelastic surface waves phenomenon with voids, gravity, initial stress, and rotation under four theories

This paper addresses a significant research gap in the study of surface waves propagation in a nonhomogeneous, within a magneto-thermoviscoelastic material of higher order, initial stress, rotation, gravity effects and voids. This study provides analytical solutions for surface waves propagating through a medium consisting of a magneto-thermoelastic material with voids under the rotation, electro-magnetic field, gravity field and initial stress. The analytical solutions are derived for the displacement components, volume fraction, temperature to Stoneley and Rayleigh waves are computed numerically and presented graphically considering the external parameters impact. Furthermore, this investigates how magnetic field, voids, gravity, initial stress and fiber-reinforced parameters influence these wave phenomena. This investigation provides valuable insights into the synergistic dynamics among electric constituents, voids, Stoneley and Rayleigh waves propagation, enabling advancements in sensor technology, augmented energy harvesting methodologies, and pioneering seismic monitoring approaches. For certain materials, numerical simulations are provided and graphically displayed. The results of this study reveal several unique cases that significantly contribute to the understanding of Rayleigh and Stoneley waves propagation within this intricate material system, particularly in the presence of voids.

Magnetic field and initial stress on a rotating photothermal semiconductor medium with ramp type heating and internal heat source

This manuscript addresses a significant research gap in the study by employing a mathematical model of photo thermoelastic wave propagation in a rotator semiconductor medium under the effect of a magnetic field and initial stress, as well as ramp-type heating. The considered model is formulated during the photothermal theory and in two-dimensional (2D) electronic-elastic deformation. The governing equations represent the interaction between the primary physical parameters throughout the process of photothermal transfer. Computational simulations are performed to determine the temperature, carrier density, displacement components, normal stress, and shear stress using the application of Lame’s potential and normal mode analysis. Numerical calculations are carried out and graphically displayed for an isotropic semiconductor like silicon (Si) material. Furthermore, comparisons are made with the previous results obtained by the others, as well as in the presence and absence of magnetic field, rotation, and initial stress. The obtained results illustrate that the rotation, initial stress, magnetic field, and ramp-type heating parameter all have significant effects. This investigation provides valuable insights into the synergistic dynamics among a magnetization constituent, semiconducture structures, and wave propagation, enabling advancements in nuclear reactors' construction, operation, electrical circuits, and solar cells.

Analysis of an initially stressed functionally graded thermoelastic medium (type III) without energy dissipation

The current investigation deals with the deformation of a non-homogeneous thermoelastic half space under hydrostatic initial stress for the Green–Naghdi model III. The medium is supposed to be rotating with a constant angular velocity. The non-homogeneous properties of the material are along the x-direction. At the first instance, the problem has been solved analytically to obtain stress and displacement components. Further, the numerical values of these expressions are evaluated using a computer program for a particular medium. The numerical values obtained are then presented graphically to show the effect of initial stress parameter and non-homogeneity parameter on the quantities.

Propagation of plane waves at the initially stressed surface of an orthotropic nonlocal rotating half space under dual-phase-lag model

PurposeThe purpose of the current manuscript is to investigate the reflection of plane waves in a rotating, two-dimensional homogeneous, initially stressed, nonlocal orthotropic thermoelastic solid half-space based on dual-phase-lag model.Design/methodology/approachThe reflection phenomenon has been utilized to study the effects of initial stress, rotation and nonlocal parameter on the amplitude ratios. During the reflection phenomenon three coupled waves, namely quasi displacement primary wave (qP), quasi thermal wave (qT) and quasi displacement secondary wave (qSV) have been observed in the medium, propagating with distinct velocities. After imposing the suitable boundary conditions, amplitude and energy ratios of the reflected waves are obtained in explicit form.FindingsWith the support of MATLAB programming, the amplitude ratios and energy ratios are plotted graphically to display the effects of rotation, initial stress and nonlocal parameters. Moreover, the impact of anisotropy and phase lags is also observed on the reflection coefficients of the propagating waves.Originality/valueIn the current work, we have considered rotation and nonlocality parameters in an initially stressed orthotropic thermoelastic half-space, which is lacking in the published literature in this field. The introduction of these parameters in a nonlocal orthotropic thermoelastic medium provides a more realistic model for these studies. The present work is valuable for the analysis of orthotropic thermoelastic problems involving rotation, initial stress and nonlocality parameters.

Effect of Initial Stress and Impedance Boundary in Transversely Isotropic Materials

This paper aimed at studying the effect of initial stress and impedance boundary surface on the elastic waves propagation in transversely isotropic materials. The governing equations of transversely isotropic materials with initial stress are treated in the [Formula: see text]-plane to obtain the phase velocities of two waves, quasi-longitudinal ([Formula: see text]) and quasi-transverse ([Formula: see text]) waves. The normal mode operation is employed to obtain the expression of the displacement components and stress components. The problem of reflection of incident waves at the impedance boundary of transversely isotropic material is also investigated in the presence of initial stress to obtain the amplitude ratios of reflected waves. The variations of displacement and force stress are illustrated with respect to the axis of propagation by employing amplitude ratio expression. The effect of initial stress and impedance parameters on the expression of displacement and force stress as well as amplitude ratios of transversely isotropic materials are illustrated graphically for a particular model.

How Do Earthquakes Stop? Insights From a Minimal Model of Frictional Rupture

AbstractThe question “what arrests an earthquake rupture?” sits at the heart of any potential prediction of earthquake magnitude. Here, we use a one‐dimensional, thin‐elastic‐strip, minimal model, to illuminate the basic physical parameters that may control the arrest of large ruptures. The generic formulation of the model allows for wrapping various earthquake arrest scenarios into the variations of two dimensionless variables (initial dimensionless stress parameter on the fault) and (dimensionless fracture energy), valid for both in‐plane and antiplane shear loading. Our continuum model is equivalent to the standard Burridge‐Knopoff model, with an added characteristic length scale, H, that corresponds to either the thickness of the damage zone for strike‐slip faults or to the thickness of the downward moving plate for subduction settings. We simulate the propagation and arrest of frictional ruptures and derive closed‐form expressions to predict rupture arrest under different conditions. Our generic model illuminates the different energy budget that mediates crack‐ and pulse‐like rupture propagation and arrest. It provides additional predictions such as generic stable pulse‐like rupture solutions, stress drop independence of the rupture size, the existence of back‐propagating fronts, and predicts that asymmetric slip profiles arise under certain pre‐stress conditions. These diverse features occur also in natural earthquakes, and the fact that they can all be predicted by a single minimal framework is encouraging and pave the way for future developments of this model.

Dynamic properties of dredger fill involved coupling action of initial stress and principal stress rotation

GCTS hollow cylinder apparatus was used to perform a series of tests on dredger fill from Tianjin under different initial stress states. This cyclic loading mode can simulate the rotation of the principal stress direction induced by wave loading. The effects of the initial intermediate principal stress parameter, initial shear stress and initial orientation angle of principal stress on softening index of dredger fill were investigated. A stiffness softening model which can consider different initial stress states was established. The test results show that when two of the three initial stress parameters remain unchanged, the softening index decreased with the increase of any other parameter. Among them, the initial orientation angle of principal stress has a great influence on stiffness softening. Based on the regression analysis of the test data, the relationship between the generalized shear strain ratio and the number of cycles under different cyclic shear stress amplitudes is proposed. Subsequently, the dynamic strength characteristics of the dredger fill were studied. It is found that the dynamic strength decreased significantly with the increasing initial angle of the principal stress, which can be accurately described by the model proposed in this article.

Effect of interaction between polarization direction and inclined force on the dynamic stability of a pre-stressed piezoelectric plate

The current study deals with forced vibration analysis of a pre-stressed piezoelectric plate with finite lengths resting on a rigid foundation, exposed to an inclined time-harmonic force. The present investigation is modeled according to a new theoretical consideration in the context of the three-dimensional linearized theory of elasticity for solids under initial stress (TLTESIS). It is assumed that the plate exhibits a polarization effect in both vertical and horizontal directions to the top surface and there is an exact clamping condition at the interface between the plate and the rigid foundation, that is, no jumping in the quantities. For obtaining the governing and boundary condition equations of our problem, the virtual work principle is used according to Hamilton's principle and the piecewise homogeneous body model. The three-dimensional displacement-based finite element model is developed for solving the system of partial differential equations and analyzing the dynamic behavior of the plate. The reliability of the solution procedure is proved by convergence analysis and comparing the results to the current literature. The target of the paper for surveying the numerical results and findings is divided into two sections. The first one presents the influence of the inclination of the dynamic external force on the forced vibration characteristics of the current model. In the second one, the influence of inclination angle, thickness ratio, aspect ratio, and initial stress parameter on the frequency response of the harmonic force are investigated in detail. As a desirable result for the designer, while a decrease in the angle of the force with the vertical axis exceeds the resonant mode of the stress, increasing values of the initial stress prevents that mode.

Broadband Strong Ground Motion Modeling Using Planar Dynamic Rupture With Fractal Parameters

AbstractDynamic rupture modeling represents a promising physics‐based approach to strong ground motion simulations. However, its application in a broad frequency range (0–10 Hz), interesting for engineering studies, is challenging. The main reason is that widely used and relatively simple planar fault models with smooth distributions of initial stress and frictional parameters, or even self‐similar initial stress, result in ground motions depleted in high‐frequency content. Here we propose an efficient approach for the linear slip‐weakening friction model on a planar fault based on the Ide and Aochi (2005, https://doi.org/10.1029/2004jb003591) multiscale model with a small‐scale random fractal distribution of the slip‐weakening distance Dc. We propose a way to combine these variations with a large‐scale deterministic dynamic model. We illustrate the approach on an elliptical model and a smooth model of the 2016 Mw 6.2 Amatrice, Italy, earthquake from low‐frequency dynamic rupture inversion. To intensify the incoherence of the rupture propagation, we also include a variation of the strength and initial stress, both correlated with Dc. These additions result in sustained high‐frequency radiation during the whole rupture propagation and omega‐square source time functions. The new model of the Amatrice earthquake generates synthetics that agree with the local ground motion model up to 5 Hz in terms of spectral accelerations while preserving the average and integral dynamic rupture parameters (e.g., stress drop, fracture and radiated energy). The fractal dynamic model can be easily implemented in any dynamic rupture propagation code and is thus readily applicable in broadband physics‐based ground motion predictions for earthquake scenarios in seismic hazard assessment.

FRICTION TEST AND PARAMETER ANALYSIS OF PRESTRESSED CONCRETE CONTINUOUS BEAM BRIDGE

The prestressed ducts of prestressed concrete continuous girder bridges are usually three-dimensionally distributed and long in length. The control of prestress loss during construction is very important. In order to ensure the effect of prestress tensioning, the test and analysis of friction parameters of prestressed ducts are particularly important. Based on the tension process of a prestressed concrete continuous beam bridge, the initial tension stress, loading time and channel friction parameters of the prestressed concrete continuous beam bridge are tested by field tests. Combined with the measured friction parameters, the finite element software Midas / Civil is used to analyse the influence of friction parameters on the mechanical properties of prestressed concrete continuous beam bridge. The results show that when the prestressed steel with bending angle not more than 40° and length not more than 70 m is stretched, the initial tension stress is suggested to be set as 20 % of the tension control force and the loading time is 5 min. The measured tunnel friction parameters are larger than the standard value, and the tension control force should be adjusted during the formal tension construction；The deflection of the key section of the main beam increases with the increase of the friction parameters, and the roof stress decreases with the increase of the friction parameters. The change of channel deviation coefficient has a greater impact on the deflection and roof stress than the change of friction coefficient.

Photothermal excitation of an initially stressed nonlocal semiconducting double porous thermoelastic material under fractional order triple-phase-lag theory

Purpose This paper aims to study photothermal excitation process in an initially stressed semi-infinite double porous thermoelastic semiconductor with voids subjected to Eringen’s nonlocal elasticity theory under the fractional order triple-phase-lag thermoelasticity theory. The considered substrate is governed by the mechanical and thermal loads at the free surface. Design/methodology/approach The normal mode technique is used to carry out the investigation of photothermal transportation. By virtue of the MATHEMATICA software, each distribution is exhibited graphically. Findings The expressions of the displacements, temperature, volume fractions of both kinds of voids, carrier density and stresses are determined analytically. With the help of the numerical data for silicon (Si) material, graphical implementations are presented on the basis of initial stress, fractional order, nonlocality and thermoelectric coupling parameters. Originality/value The present study fabricates the association of Eringen’s nonlocal theory and the stress analysis in a semiconducting double porous thermoelastic material with voids, which significantly implies the originality of the conducted work.

Vibration of initially stressed nonlocal irregular nanoplate using wave propagation approach

The vibration analysis of pre-stressed nonlocal irregular nanoplate is discussed in this study. To consider the nonlocal effects, Eringen's nonlocal elasticity model are adapted. Biot`s theory is used to generate the new governing equation as well as its closed-form solutions including the initial stress parameter. Governing equations considering small length scale, initial stress, and surface irregularity were solved by the wave propagation approach. A novel frequency equation is explored in relation to a small length scale, initial stress, and surface irregularity. To understand the reactions of the considered nanoplate in terms of natural frequency, the numerical calculations are done and the results are shown graphically. The findings provide a better declaration for vibration analysis of the nonlocal initially stressed irregular nanoplates. It has been observed that, the increase of the small length scale parameter decreasing the natural frequencies and the increase of initial stress and surface irregularity parameters increasing the natural frequencies throughout the computation frequencies of vibrating nanoplate. In addition, the existence of nonlocal, initial stress, and irregularity parameters effect the natural frequency of vibrating nanoplates significantly. Furthermore, the findings obtained could be relevant in designing of nanodevices in which nanoplate are the most common nano element.

Scale effects on the torsional surface waves propagation in an initially stressed dissipative nanoplate

The effects of small length scale on the torsional surface waves propagating in a pre-stressed dissipative nanoplate were examined in this paper. Biot’s incremental deformation principle as well as nonlocal elasticity theory were implemented to form the governing and frequency equations of torsional surface waves in nanoplate under considered conditions. In this work, we proposed a new approach to determine the phase velocity of torsional disturbances. Different categories are used to investigate the dispersion relations such as: wave number, scale coefficient, initial stress parameter, and dissipation coefficient. The results show that small length scale influences causes torsional dispersion of the wave propagation, which disappear in local elasticity theory. In addition, it is recognized that the torsional surface waves propagating in the pre-stressed dissipative nanoplates can be differentiated in a clear manner from those propagated in the absence of small length scale effects. The initial stress parameter can also be utilized to change the characteristics of the torsional surface wave's phase velocity in nanoplates. It is also observed that, the dissipation has a great effect on the phase velocity of torsional surface waves in propagating in the nanoplate. Therefore, this research is theoretically useful to convey information on nonlocal and dissipation properties of the nanomaterials: for example, through a precise measurement of the phase velocity of torsional surface wave propagates in a nanocomposite material by presence of the medium’s dissipation. This work could be useful in understanding the way of designing the Nano devices and Nano resonators.

Plane waves in an initially stressed rotating magneto-thermoelastic half-space with diffusion and microtemperatures

ABSTRACT The present analysis is concerned with the reflection of plane waves at the free surface of an isotropic, homogeneous, initially stressed rotating magneto-thermoelastic medium with diffusion and microtemperatures. It is noticed that there exist five sets of coupled waves in addition to an independent microtemperature wave, which travels through the medium with distinct speeds. The entire thermoelastic medium is rotating with a uniform angular velocity. Using appropriate boundary conditions, the amplitude and energy ratios of various reflected waves are computed analytically. For a particular model, the numerical values of the amplitude ratios are presented graphically to estimate and highlight the effects of initial stress, magnetic field, angular velocity, diffusion and microtemperature parameters. The expressions of energy ratios obtained in the explicit form are presented graphically as functions of the angle of incidence. It is verified that there is no loss of energy at the boundary surface during the reflection phenomenon.

Torsional Wave in a Dissipative Cylindrical Shell Under Initial Stresses

The dispersion relation of torsional wave in a dissipative, incompressible cylindrical shell of infinite length incorporating initial stresses effects is investigated. The governing equation and closed form solutions are derived with the aid of Biot's principle. Phase velocity and damping of torsional wave are obtained analytically and the influences of dissipation and initial stresses are studied in details. We proposed a new method for obtaining the phase and damping velocities of torsional wave in a complex form. Numerical results analyzing the torsional wave propagation incorporating initial stress effects are analyzed and presented in graphs. The analytical and numerical solutions reveal that, the dissipation as well as the initial stresses have notable impacts on the phase velocity of torsional wave in a pre-stressed dissipative cylindrical shell. The numerical results reveal that, the initial stresses and dissipation, considerably, effect the phase velocity of the torsional wave. It has been observed that, any change in dissipation parameter (δ) produces a substantial change in damping velocity of torsional wave. In addition, it can be seen that, the phase velocity increases as the initial stress parameter increases. Finally, the result of numerical simulation illustrated the influence of dissipation and initial stresses on damping and phase velocities of torsional wave propagation. The conclusion made shown the consistency with the Biot's incremental deformation theory, and the effective on model such as engineering mechanics and displacement of particles.

Dispersion of Love-type wave and its limitation in a nonlocal elastic model of nonhomogeneous layer upon an orthotropic extended medium

This research paper investigates the Love-type surface wave dispersion in a nonlocal elastic nonhomogeneous medium over a nonlocal orthotropic semi-infinite medium under the effect of interior initial stress component. A generalized linear elasticity theory with the nonlocal effect in the fundamental stress-strain relation is adopted to address the equation of motion in layered media. In the case of time-harmonic plane wave propagation, PDEs (cf. equations of motion) of the nonlocal elasticity are reduced to closed-form singular differential equations. The equation of dispersive wave is derived using appropriate plane stress-displacement-continuity conditions of the model. The dispersion of Love-type wave and its limitation in a nonlocal elastic media are analysed graphically using MATLAB software. For the specific model, it is observed that the attenuation of the dispersion of Love-type wave depends on a nonlocal parameter. Also, the dispersive wave becomes nondispersive with zero attenuation for large values (∼0.4) of the nonlocal parameter. In the case of dispersive wave, variation of the phase velocity of the fundamental wave mode for different values of nonlocality, nonhomogeneity, wave number and initial stress parameters are shown graphically. Some special cases are deduced from the original dispersion equation and validated with the published literature.

The effect of initial stress and rotation on a nonlocal fiber‐reinforced thermoelastic medium with a fractional derivative heat transfer

AbstractIn the present paper, the theory of multi‐phase‐lags with fractional derivative heat transfer thermoelasticity was used to study the wave propagation on a nonlocal fiber‐reinforced thermoelastic medium. The exact expressions for the displacement components, temperature, and stress components are obtained by using the Fourier and Laplace transforms. The comparisons are shown graphically to explore the effects of rotation, initial stress and fractional order parameters as well as a nonlocal parameter on different physical quantities. Numerical computations are carried out with the help of Matlab software.

Analysis of Dilatation Waves Propagation in an Irregular Single-Walled Carbon Nanotube Under Initially Stresses

This article studies the propagation of dilatation waves in an initially stresses single-walled carbon nanotube (SWCNT) with surface irregularity using Donnell thin shell approach. Taking into account the effects of surface irregularity and initial stresses, propagation of dilatation waves is studied and dispersion curves are plotted for in several figures. The effects of surface irregularity and initial stresses are confirmed by comparing obtained numerical results with those in cases of uniform and initial stress-free SWCNT. Obtained results turn out that, the increase of surface irregularity parameter increases the natural frequency of dilatation waves, while the increase of the initial stress parameter decreases the natural frequency of dilatation wave propagating in the single-walled carbon nanotube. To the author best knowledge, effects of surface irregularity and initial stresses on the dilatation waves propagation in a single-walled carbon nanotube has not yet been done before. The previous studies were devoted to the uniform and initial stresses-free carbon nanotubes. It should be emphasized that the dilatation waves propagating in a pre-stressed irregular single-walled carbon nanotube is novel, workable, and at the beginning of the path. In this manner, understanding the influences of surface irregularity as well as initial stresses on the natural frequency of dilatation waves may serve as useful references for the applications and designs of nano oscillators and nanodevices, in which single-walled carbon nanotubes act as the most prevalent nanocomposite structural element.

SH wave propagation in a periodic cement-based piezoelectric layered barrier

The purpose of this study is to investigate SH wave in the periodic cement-based piezoelectric layered barrier to meet the needs of vibration control in complex engineering environments and improve the application of periodic vibration isolation barrier in civil engineering. The governing equation of SH wave in periodic barrier is established based on the periodic theory of phononic crystals. The band structures are calculated by plane wave expansion method, the transmission characteristics are computed by transfer matrix method, and the attenuation effect of the periodic barrier is verified by finite element method. The effects of geometric parameters, material parameters and initial stress on band structures are analyzed in details. The numerical results show that the number of unit cells, initial stress and material parameters of the periodic barrier have significant effects on the band gap. As the lattice constant of the structure increases and the equivalent elastic modulus decreases, the lower boundary and the width of the band gap decrease. With the increase of tensile stresses, whether the lower and upper boundary or the width of the band gap will all increase, while they are decrease with the increase of compressive stresses. This work provides an alternative avenue for the design of periodic layers as wave barriers.

Transverse waves incident at the free surface of an initially stressed dissipative half-space

In this work, an attempt is done to apply Biot`s incremental deformation theory to find out the effects of initial stresses on the reflected transverse waves (S-waves) at a free surface of dissipative half-space medium. Equations of motion and its corresponding solutions are derived in lights of Biot`s theory. The impact of initial stresses and medium`s dissipation on the reflected transverse wave are studied in detail. Numerical calculations carried out using Aswan geological crustal structure and the results are presented graphically. Numerical findings reveal that, the initial stresses and the medium dissipation effects the reflection coefficients of transverse wave considerably. In addition, it has been noted that, the phase velocity decreases considerably as the initial stress parameter increases. Since the crust of the Earth, , is dissipative and initially stressed medium, thus understanding the effects of these parameters may help seismologists to get accurate results of reflected seismic transverse wave at the surface of Earth crust.